1. Field of the Invention
The present invention relates to techniques for performing the driving control of a vehicle by use of map data.
2. Description of the Related Art
On-board systems for performing the driving control of a vehicle by use of map data including attribute data of roads (information about the grade of each road, and the like) are conventionally known (for example, JP-A-7-192194). The on-board system disclosed in JP-A-7-192194 calculates a current position of a vehicle, and then estimates, from the calculated current position and map data, a road through which the vehicle is going to travel from now. The on-board system disclosed in JP-A-7-192194 uses estimated attribute data of the road to control the operation of elements such as an automatic transmission, an engine, and a suspension. Incidentally, there are various kinds of on-board systems that use map data. For example, there is an on-board system in which attribute data of each road includes data indicating a position of a temporary stop line on the road, and the attribute data is used to judge whether or not a vehicle has approached the temporary stop line, and then if it is judged that the vehicle has approached the temporary stop line, the speed of the vehicle is automatically reduced. In addition, there is also an on-board system in which, from information about a road shape included in map data, a judgment is made as to whether or not a vehicle has approached a railroad crossing, and if it is judged that the vehicle has approached the railroad crossing, the speed of the vehicle is automatically reduced.